(1) Field of the Invention
The present invention relates to sound radiation. More particularly it concerns an improvement in an underwater barrel stave acoustical projector that has use as a mobile target capable of simulating the spatial extent of a submarine. The barrel stave projector is a flextensional device that drives a series of concave staves in the radial direction by the application of a force in the axial direction produced by a stack of piezoelectric ceramic rings in response to an electrical input. Thus, the projector essentially operates as a mechanical amplifier, coupling the longitudinal vibration of a piezoceramic driver to the transverse vibration of a passive shell comprised of a plurality of barrel staves.
(2) Description of the Prior Art
In prior art systems a barrel stave projector used identical staves made of curved flexible bars arranged so that the profile of the projector is similar to an hourglass which is circular in horizontal cross-section at all points from the top to the bottom thereof. This configuration provided a very limited range of resonant frequency for such a projector.